PROJECT SUMMARY Bio-layer interferometry (BLI) reports on the kinetics of macromolecular binding interactions and structural changes. Recent advances in bio-layer interferometry (BLI) instrumentation design have led to the availability of commercial instruments that are robust, simple to use, and permit high-throughput data acquisition with small volume and concentration samples. With these advances, access to BLI technology is now essential for laboratories using biochemical approaches. The University of California at Santa Cruz hosts several NIH-funded biochemistry and structural biology researchers who are advancing studies of complex cellular mechanisms relevant for the circadian clock, cell division, maintenance of telomeres, childhood viruses, immune response regulators, and neurodegeneration. We request funding for an Octet RED384 BLI instrument, which will be incorporated into an existing macromolecular structure and function core facility. The ability to study macromolecular interactions with a label-free approach that uses little precious sample and permits kinetic analysis will significantly upgrade the current capabilities of our research cluster.